Process for treating yarns, filaments and fibers



June 20, 1961 E. c. ATWELL 2,988,799

PROCESS FOR TREATING YARNS, FILAMENTS AND FIBERS Filed Sept. 24, 1956 3Sheets-Sheet 1 INVENTOR EVERETT c ATWE LL ATTORNEYS June 20, 1961 E. c.ATWELL PROCESS FOR TREATING YARNS, FILAMENTS AND FIBERS Filed Sept. 24,1956 3 Sheets-Sheet 2 INVENTOR EVERETT C. ATWELL BYW@ W ATTORNEYS June20, 1961 E. c. ATWELL PROCESS FOR TREATING YARNS, FILAMENTS AND FIBERSFiled Sept. 24, 1956 3 Sheets-Sheet I5 FIG.4.

INVENTOR EVERETT C. ATWEL L Bywwfw ATTORNEYi Delaware Filed Sept. 24,1956, 'Ser. No. 611,547 2 Claims. (CI. 28-72) This invention relates tothe crimping of filaments, yarns and fibers. More particularly, theinvention is concerned with novel methods and apparatus for continuouslyimparting selected and uniform crimp patterns to filaments, yarns andfibers while simultaneously rendering the same heat set;

Filaments, yarns and fibers which may be processed according to theinvention are those comprising synthetic, thermoplastic high molecularproducts ,of long chain molecular structure and capable of being heatset. Typical of such materials are the synthetic linear polyamides(nylon), acrylics and polyesters of the type shown in US.

Patent.2,465,3l9 including the product known, as Dacron (polymericethylene terephthalate).

Suitable synthetic linear polyamides are described in US Patent2,071,250, such as poly-hexamethylene adipamide, poly-decamethyleneadipamide, and poly-hexamethylene sebacamide. Other polyamides suitablefor use herein are the products obtained by self-condensation of 6 aminocaproic acid'or otheromega-amino carboxylic acids, or the polymersobtained from lactams such as epsilomcapro'lactam.

The term heat set as used herein is utilized in a generic sense and isintended to indicate a condition in which the yarns, filaments or fibersshow no appreciable shrinkage afterimmersion in hot or boiling water andsubsequent drying. For the purposes of the invention, heat set yarns,fibers and filaments measured under just suificient load to straightenout the crimp, immersed fifteen minutes in 7 water at, or close to, theboil, air dried in slack condition and remeasurcd under the same load aspreviously, will not. shrink more than 1.0% in length.

It has previously been proposed (US. Patent 2,216,412)

to produce crimped, low density'bulk yarns or the like by a methodinvolving the steps of (a) softening the yarn with water, steam or othersoftening agent; (b) subjecting the'softened yarn, either subsequent tothe softening treatment or simultaneously therewith, to lateral pressureexerted by the meshing together of suitable crimping rolls thus creatinga temporary crimp; (c) immediately subjecting the yarn to a rubbingaction in a transverse direction whereby the yarn assumes an open or lowbulk condition; and (d) thereafter drawing the yarn over a heated plate"under low tension to set the same in its open or low bulk :condition. a

According to another method, (U.S. Patent 2,575,833), the yarn or fibersare gripped between rollers, with or without teeth, and forcedinto achamber where the material is positioned in a zig-zag pattern whichforms sharp angular bends or crimps with longer intervening straightsections. The'thus crimped yarn is then held compacted under constantpressure to retain the crimp and Water, steam, superheated water vaporor the vapors of certain organic liquids introduced thereto for thepurpose of soft- -enin'g the crimped material after which the materialis removed from the treating chamben.

Other types: of crimping procedures comprise highly "twisting yarn orthelike, setting the twist therein and then 'back twistingto obtainaproduct having a random crimp, low bulk and high elongation.

"rnentioned procedures in thatit "provides methods and Thepresentinvention difiers uniquely from the abovemeans for heat setting andimparting a desired crimp pattern to synthetic thermoplastic polymericyarns, filaments and fibers, uniformly and continuously in a singleoperation without the necessity of using softening agents such as water,steam or organic vapors prior to or during crimping and without theapplication of subsequent drying and/ or heat setting operations. I

As will be appreciated from the foregoing, the principal object of thepresent invention is the provision of improved methods and apparatus forcrimping and heat setting synthetic thermoplastic yarns, filaments andfibers.

A more specific object is to provide means for continuously andsimultaneously producing a uniformly heat set, crimped yarn, filament orfiber.

Another object of the invention is the provision of methods andapparatus for imparting a crimp of selected pattern to yarns, filamentsor fibers of synthetic long chain, high molecular weight polymericthermoplastics by subjecting the thermoplastic to controlled pressure ofmeshed crimping rolls at a temperature at least equal to the secondtransition step of the thermoplastic.

Other specific objects are to provide method and/or apparatus for: a

(a) supplying regulated, continuous and uniform heat to the crimpingrolls;

'(b) positively controlling the tension on the crimped yarn or the likeas it emerges from the crimping rolls and as it is taken up on asuitable bobbin or the equivalent;

(0) retaining the crimped yarn in a compact form as it comes off thecrimping rolls and, in the case of multifilament yarns, avoiding openingup of the yarn so that it is maintained as far as possible in a formresembling a monofilament yarn.

Other objects will also be apparent from the following detaileddescription of the invention and the accompanying drawings wherein:

FIGURE 1 is a diagrammatic view of an-assembly for crimping and heatsetting according to the invention;

FIGURE 2 is a horizontal sectional view of the means for heating thecrimping rolls;

FIGURE 3 is a plan view of the crimping rolls;

FIGURE 4 is a horizontal sectional View of means utilized according tothe invention to control tension on the crimped material as it leavesthe crimping rolls; and

FIGURE 5 is a horizontal sectional view of means for winding up thecrimped product in accordance with the present invention.

Referring more particularly to the drawings, FIGURE 1 shows a suitablesupply package 2 having yarn of nylon or other synthetic polymericthermoplastic material wound thereon. The yarn may be multifilament ormonofilament yarn of any desired denier, e.g. 10450 denier. As shown inFIGURE 1, the yarn 4 is drawn off the package 2 and passed throughsuitable guide means 6 and tension means 8, the tension on the yarn atthis point generally ranging between 0.03 and 0.30 grams per denier.From tension means 8, the yarn is passed through further guides 10 and12, the latter preferably being a comb guide, or the equivalent, to apair of crimping rolls 14 and 16.

Rolls 14 and 16 comprise a pair of revolving, matching gears which areinternally heated, in the manner deheat setting. Suitable screw means 18are provided for adjusting the clearance between the meshed surfaces togive the desired lateral pressure on the yarn during the crimping andheat setting. Roll 14 may be revolvably conduits 57 and 58.

mounted on a suitable shaft 20 which is rotatable within bearing means22 but fixed against lateral movement. As indicated, however, roll 16 ismovable laterally with its supporting shaft 24 and bearing 26 by screwmeans 18. The lateral pressure exerted on the yarn by the crimping rollssimultaneously softens the thermoplastic material, forms the desiredcrimp therein and heat sets the same against loss of crimp pattern anddimensional loss during the short contact periods which are utilized. Itwill be appreciated that the lateral pressure exerted on the yarn can bewidely varied depending upon other operating factors and the resultsdesired.

On emergence of the yarn from the mesh of the rolls 14 and 16, the yarnis still hot and in a plastic state at the final point of roll contact.Therefore, any tension applied to the crimped yarn on the delivery sideof the crimping rolls permanently reduces both the amplitude and crimpcount. If enough tension is applied, all of the crimp will be removedand the yarn, being heat set under tension, also will not meet the heatset requirements, as defined heretofore. A most important aspect of theinvention, therefore, relates to the manner in which the yarn is takenaway from the hot crimp rolls under negligibly low tension thuspermitting the crimped, hot plastic yarn to cool and set in the fullcrimped pattern imparted by the crimp rolls. To this end, the yarn isdrawn, after it leaves the crimping rolls, over a ball bearing pulley 28which is mounted at the inner end of an arm 30. The latter is pinionedat a fulcrum 32 and balanced by spring means 34 which are adjustable asto tension by control post 36. Pulley arm 30 serves to take up any slackin the yarn and at the same time prevents damage thereto due toexcessive tension during periods of adjustment, e.g. when starting up.Arm 30 also indicates the relative tension and uniformity of tensionduring the period of operation.

After passing around a fixed pulley 38, the crimped yarn 4 is drawnthrough guide means 39 into the nip of a pair of tapered, rubber coveredrolls, 40 and 42. These rolls are so arranged, as subsequently discussedin detail, that the -takeup speed of yarn drawn therethrough can beexactly matched with the delivery of crimped yarn from crimping rolls 14and 16.

The yarn leaving the nip of takeup rolls 40 and 42 is passed over asuitable reciprocating traverse guide 44 and wound up on a yarn carrier46 of conventional type, e.g. an aluminum spool or the like. Asdiscussed hereinaft r, carrier 46 is arranged for rotation at variousspeeds so that the tension on the yarn as it is wound up can be adjustedover a wide range.

The foregoing describes in a general way the broad aspects of thepresent invention as exemplified by FIG- URE 1 Certain importantspecific features of the invention are shown in FIGURES 2-5. Forinstance, FIG- URE 2 illustrates preferred means for heating the gearedrolls 14 and 16. According to FIGURE 2, a suitable reservoir 48 isprovided for the heating fluid 50 which may be a chlorinated diphenyl.The preferred heating medium is any material of low vapor pressure athigh temperature, which is fluid at room temperature. as. well as atelevated temperature and which does not readily oxidize or decomposeduring prolonged periods up to 500 F. As shown, by the arrows, the hotfluid is drawn out of the bottom of the reservoir through conduit 52 bysuitable pump means 54 and forced through a header pipe 56. The latteris branched as. shown to form two Conduit 57 leads into crimping roll 16through a rotary union 60 while conduit 58 feeds to roll 14 in a similarmanner. For simplicity, only the connection of branch 57 to roll 16 isshown although it will be understood that there is an identicalconnection between branch 58' and roll 14. As indicatedin FIGURE 2, theheating fluid is forced from branch 57' and the rotary coupling 60through a tubular conduit, 62. from 4 whence it passes into an annularheating space or chamber 64 within crimping roll 16. From heatingchamber 64, the fluid flows through a centrally located tube 66 whichextends within roll 16 through conduit 62 and coupling 60. Tube 66communicates with a suitable return conduit 68 which leads the fluidback to reservoir 48. The reference numerals 62', 64', 6'6 and 68'designate the elements corresponding with members 62, 64, 66 and 68 inthe connection between branch conduit 58 and roll 14.

The fluid in reservoir '48 may be heated in any desirable manner, forexample, by means of electrical heating coils or the like positionedadjacent the base of the reservoir. The temperature of the fluid may bewidely varied as long as it is suflicient to heat the rolls to atemperature at least equal to the second transition point of thematerial being treated. Generally speaking, an operable temperaturerange for the crimping rolls runs from a minimum of about 250 F. forlinear polyamides and polyesters (e.g. nylon and Dacron) up to the tackpoint of the material. The preferred temperature range is between about360 F. and the tack point (e.g. about 400 F. for nylon).

The time of contact between the yarn or the like and the heated crimpingrolls can be widely varied and depends upon the nature of the materialbeing treated, denier and crimping temperature. In using monofilamentsand multifilament yarns of the order of 15 to 30 denier at 400 F. acontact time in the order of second is ample to provide a good, fullyheat set, crimped yarn. Generally speaking, from A to 1 second, usingthe shorter lengths of time for higher temperatures gives satisfactoryresults.

A thermostat 70 may be provided in the reservoir for the purpose ofoperating the heating means and maintaining a desirably uniformtemperature for the heating fluid. Preferably, the various conduits andother parts of the heating system hereinabove described are insulated inorder to minimize heat losses. Motor 72 serves to 0p erate pump means 54and may comprise a small fractional horsepower motor directly coupled tothe pump shaft. The speed of this motor may be controlled by a rheostat(not shown) in the power supply line to the motor.

The pipe connections 62 and 66 and 62 and 66' between the crimping rollsand the heating system are also shown in FIGURE 3. As illustratedtherein, the rolls 14 and, 16 each have two zones of meshing teeth,namely, a relatively wide band 74 and a narrower band 76, and areoperated by suitably driven chain and sprocket means designated by thenumeral 77. As indicated, the narrow band of teeth 76 on top roll 16meshes with the corresponding band 76 in the lower roll 14. The top rollis turned by its drive shaft 24 through the sprocket and chain means 77.The lower roll 14 is driven by upper roll 16 through the meshing of thetwo narrow bands 76. The teeth in these narrow bands 76 are cut severalthousandths of an inch in advance of the teeth in the crimping area 74,the purpose of such misalignment being to take the driving load off thefibers while they are at the interface of the meshed teeth.

FIGURE 4 shows another important feature of the invention, namely, theconstruction and mode of operation of the takeup rolls 40 and 42. Theserolls and the means associated therewith, discussed hereinafter, areadapted to take the yarn up as the latter leaves the crimping rolls 14and 16 at a sufficiently low tension to avoid removing vthe crimp whichhas been imparted thereto. To this end,

axle 78 and driven by a suitfixed position by means of, a supportingmember 80.

1Roll42, on the otherhand, is mounted for vertical movement'andis-adjustable'so as to regulate the interfacial pressure between theoppositely tapered, rubber covered surfaces of the rolls. Thus, asshown, roll 42 is provided with a shaft or axle 82 mounted insuit'ableblock bearings 84Land 86, the latter being movable vertically in a pairof slots 88 and 90, respectively, formed in supporting frame 80.Threaded post means 92 are provided to permit adjustment of theinterface pressure of rolls 40 and 42 byvertical positioning of thebearings 84 and 86 within their respective slots 88 and 90.

The sprocket'79 is selected asto diameter or number of teeth so thatwhen yarn guide 39 is located midway between the ends of the taperedrolls on cylinders 40 and 42, the linear speed of the yarn isapproximately equal to that of the fully crimped yarn being deliveredfrom the crimping rolls 14 and 16. The desired positioning of guide 39is eifected by providing the same with a threaded end 93 which receivesa threaded shaft 94. The latter is mounted in supporting frame 80 and isrotatable by handle means 96 to properly position guide 39.

The chain and sprocket means 77 and 79 associated with the crimpingrolls 14 and 16, and rolls 40 and 42, respectively, as well as thetraverse guide 44 and windup spool 46 may all be powered from a singlemotor through suitable gears or chains. Accordingly, there is generallyno need for adjustment of guide 39 if this guide is properly positionedat the start of operations. If, however, the tension on the yarnchanges, as indicated by the pivoted arm 30 of FIGURE 1 due, forexample, to the accumulation of dirt or size from the yarn, or if thetemperature of the crimping rolls should change appreciably, somereadjustment of guide 39 by turning handle means 96 in a clockwise orcounter-clockwise direction may be desirable. In this way, the taperedsurfaces of the rolls 40 and 42 may be used to increase or decrease thetakeup tension or speed as may be necessary. The motor used to drive thecrimping and takeup rolls, traverse guide and spool may be a onehorsepower unit with internal gear reduction. Alternatively, a largepump motor may be utilized.

A further advantage of the takeup rolls 40 and 42, as hereinabovedescribed, is that they permit the crimped product to be subsequentlywound up on the bobbin 46 of FIGURE 1 at any desired tension withouttaking out the crimp imparted by rolls 14 and 16. In other words, rolls40 and 42 provide means for taking the yarn off crimping rolls 14 and 16at speeds and/or tensions which are sufiiciently low to have nosignificant effect upon the crimp after which the yarn can be wound upat significantly higher speeds or tensions on bobbin 46 in aconventional cross wind or the like by means of the traverse member 44At this stage, the crimp has become permanently set in the yarn so'thatthere is no danger of removing the same in the final winding operation.

Another significant aspect of the invention is the arrangement forwinding the crimped product on bobbin or spool 46 as shown in FIGURE 5.More specifically, the bobbin 46 is supported upon a rotatably mountedshaft 98, one end of which is mounted on ball bearings 100 in a housing102 fixed to a supporting frame indicated by the reference numeral 104.The end of shaft 98 carries a head 106 of steel or the equivalent forthe purposes hereinafter apparent.

The means for driving bobbin or spool 46 for the purpose of winding theyarnthereon include a shaft 108 mounted for rotation in a supportingmember 110* and driven by a suitable motor (not shown) through a beltand pulley arrangement .112 which is operatively associated with theshaft at the outer end thereof.

The inner end of shaft 108 carries a head 114 of molded; plastic or thelike in which there are embeddeda number of permanentmag'ne'tsdesignated by. the refer- ;ence numeral 116., Two of these magnetsarex'shown-in FIGURE 5 although it will be appreciated that any numberthereof, for example, four, .positioned equidistant from the shaft 108,maybe utilized.

,Theinner end ofishaft head 1:14fis recessed as shown at 118 toexposethe magnets 116 and receive the steel head 106 of shaft 98'. in themanner shown. Screw means are provided for the purpose of adjustingthe'jclearance between head 106 and magnets 116 so as to change themagnetic coupling force exerted by these parts.

It will be appreciated from the foregoing description that, as the driveshaft .108 is rotated, the magnetic force created by magnets 116overcomes the inertia of the spool 46 and causes the same to rotate. Thelinear speed of the spool barrel surface without a yarn load exceeds thelinear speed of the yarn being delivered to the spool from the nip ofthetakeup rolls 40 and 42. The linear speed of the yarn as it is takenluponspool'46 can be such as the crimp roll diameter, crimp roll speed, crimproll temperatureand the denier of .the yarn being processed. Byadjusting the magnetic clearance between head 106 and the magnets 116 bymeans of screw 120, a wide range of tensions may be placed on the yarnas it is wound onto the spool. As indicated heretofore, the tension onthe yarn at this point exceeds that on the yarn entering thetakeup rolls40 and 42 but even though these relatively high tensions are sufficientto pull the yarn out straight and free of crimp configuration, the crimpis not impaired, due to the low tensions used with rolls 40 and 42.Accordingly, when the yarn is taken from the spool in visuallycrimp-free condition, and put into water or steam, or the tensionthereon relaxed, the crimp returns substantially instantaneously. Thus,yarn processed according to the invention, even though subjected totensions in winding, warping, spooling or other operations necessary toweave or knit into fabric Will regain its crimp in the boil-01f anddyeing operations which normally follow.

From the foregoing, it will be recognized that the present inventionprovides uniquely improved methods for simultaneously heat setting andcrimping yarns, filaments or fibers of nylon or other syntheticthermoplastic material by the steps of drawing the material through apair of meshing and crimping rolls or gears shaped to give the desiredcrimp configuration, internally heating the rolls to a temperaturesufficient to set the material, i.e. to a temperature at least equal tothe second transition point of the material, maintaining the material incontact with the internally heated rolls for a time suflicient to heatset the same, thereafter taking up the yarn at a relatively low tensionbelow the point at which the crimp would be removed from the materialand then winding up the yarn thus taken up at a higher tension. Otheraspects of the invention comprise taking up the crimped product from themeshing or crimping rolls at a rate of speed substantially equal to thatof the product as it leaves the rolls and the invention includes novelmeans for accomplishing this. Unique magnetically operable means forwinding up the crimped yarn or the like are also provided.

Various modifications may be made in the invention described hereinwithout in any Way deviating from the scope thereof as defined in thefollowing claims wherein:

I claim:

1. A method of producing a uniformly crimped, heat set yarn ofthermoplastic synthetic linear polymer which comprises providing asupply of said yarn in the uncrimped, non-heat set state, passing saidyarn continuously from said supply into the nip of a pair of internallyheated, driven crimping rolls maintained at a temperature sufficient toheat said yarn to a temperature at least equal to the second transitionpoint of the polymer and below the tack point thereof, maintaining theyarn be- -tween said rolls for a period of time suflicient to simul-:taneously crimp and heat'set the same, the heat set being such that'thepolymer, upon cooling, shows substantially no shrinkage after immersionin hot water followed by drying in the slack conditions; dischargingsaid yarn from the crimping .rolls in the hot plastic state and allowingthe discharged yarn to cool and set into the crimped pat- :tern of saidrollswhile said yarn is in a predominantly unsupported, essentiallyslack-free state and under negligible .tension, taking up said cooled,set yarn at a rate equal to the rate at which it is discharged from thecrimping rolls, measuring the tension on said yarn throughout thecooling and setting thereof between its point of discharge and takeup,adjusting the'takeup path and the distance of takeup to compensate forany increase in tension on the yarn as it is being cooled and set, andthereafter collecting the cooled and crimped material from said takeupunder tension, the heat setting treatment with said crimping rollsconstituting the sole essential heating treatment between said crimpingand cooling operations.

2. The method of claim 1 wherein the yarn is nylon,

into the nip of a pair of tapered takeup rolls, the rate of yarn takeupbeing maintained the same as the rate of yarn discharged from thecrimping rolls by adjusting the point at which the yarn is passed intothe nip of said tapered rolls.

References Cited in the file of this patent UNITED STATES PATENTS2,453,332 Millhiser NOV. 9, 1948 2,668,430 Laros Feb. 9, 1954 2,669,001Keen Feb. 16, 1954 2,733,122 Herele et a1 Jan. 31, 1956 2,751,661Shattuck June 26, 1956 2,758,357 Goodhue Aug. 14, 1956 2,758,358Shattuck Aug. 14, 1956 2,778,090 Hasler Jan. 22, 1957 FOREIGN PATENTS1,126,000 France July 23, 1956

1. A METHOD OF PRODUCING A UNIFORMLY CRIMPED, HEAT SET YARN OFTHERMOPLASTIC SYNTHETIC LINEAR POLYMER WHICH COMPRISES PROVIDING ASUPPLY OF SAID YARN IN THE UNCRIMPED, NON-HEAT SET STATE, PASSING SAIDYARN CONTINUOUSLY FROM SAID SUPPLY INTO THE NIP OF A PAIR OF INTERNALLYHEATED, DRIVEN CRIMPING ROLLS MAINTAINED AT A TEMPERATURE SUFFICIENT TOHEAT SAID YARN TO A TEMPERATURE AT LEAST EQUAL TO THE SECOND TRANSITIONPOINT OF THE POLYMER AND BELOW THE TACK POINT THEREOF, MAINTAINING THEYARN BETWEEN SAID ROLLS FOR A PERIOD OF TIME SUFFICIENT TOSIMULTANEOUSLY CRIMP AND HEAT SET THE SAME, THE HEAT SET BEING SUCH THATTHE POLYMER, UPON COOLING, SHOWS SUBSTANTIALLY NO SHRINKAGE AFTERIMMERSION IN HOT WATER FOLLOWED BY DRYING IN THE SLACK CONDITIONS,DISCHARGING SAID YARN FROM THE CRIMPING ROLLS IN THE HOT PLASTIC STATEAND ALLOWING THE DISCHARGED YARN TO COOL AND SET INTO THE CRIMPEDPATTERN OF SAID ROLLS WHILE SAID YARN IS IN A PREDOMINANTLY UNSUPPORTED,ESSENTIALLY SLACK-FREE STATE AND UNDER NEGLIGIBLE TENSION, TAKING UPSAID COOLED, SET YARN AT A RATE EQUAL TO THE RATE AT WHICH IT ISDISCHARGED FROM THE CRIMPING ROLLS, MEASURING THE TENSION ON SAID YARNTHROUGHOUT THE COOLING AND SETTING THEREOF BETWEEN ITS POINT OFDISCHARGE AND TAKEUP, ADJUSTING THE TAKEUP PATH AND THE DISTANCE OFTAKEUP TO COMPENSATE FOR ANY INCREASE IN TENSION ON THE YARN AS IT ISBEING COOLED AND SET, AND THEREAFTER COLLECTING THE COOLED AND CRIMPEDMATERIAL FROM SAID TAKEUP UNDER TENSION, THE HEAT SETTING TREATMENT WITHSAID CRIMPING ROLLS CONSTITUTING THE SOLE ESSENTIAL HEATING TREATMENTBETWEEN SAID CRIMPING AND COOLING OPERATIONS.